first lady michelle obama traveled with the president today and visited patients and staff at some of the hospitals that treated the wounded. brian? >> lester holt in boston for us tonight. lester, thanks. >>> we shift our attention now out west to the huge concussion and fire that tore through the town of west texas last night. a massive explosion at a fertilizer supply outlet. west is about 20 miles north of waco. it only covers a couple dozen blocks but after the blast which actually registered a 2.1 on the richter scale, a big part of the community is simply gone today. while it is unclear as of now how many people have been killed the mayor says 30 to 40 people are missing. a lot of those first responders. 160 more are injured. nbc's miguel almaguer is at the scene for us tonight. miguel, good evening. >> reporter: brian, good evening. that explosion took place a mile away from here. we have been asked to keep our distance as rescue teams search for the missing. it's feared at least 15 are dead. as you mentioned, 160 wounded. officials worry both those numbers may climb. the blas